[PATCH v2 2/2] ARM: dts: samsung: Add Hardkernel ODROID-U2

[Josef Schlehofer <pepe.schlehofer@gmail.com>]

ODROID-U2 is a single board computer from Hardkernel based on the
Samsung Exynos4412 Prime SoC with 2 GB of LPDDR2 RAM. It is the
predecessor of the ODROID-U3 and shares most of its design:
- microSD card slot and eMMC module socket
- SMSC LAN9730 10/100 Ethernet on HSIC0
- SMSC USB3503A hub on HSIC1 with two USB 2.0 host ports
- micro-HDMI port with CEC
- MAX98090 audio codec with a 3.5 mm headphone jack and an on-board
  digital microphone
- MAX77686 PMIC
- 2-pin header for an optional PWM controlled cooling fan
- blue heartbeat LED

Unlike the ODROID-U3, the micro-USB port has no VBUS supply switch, so
it can only work in peripheral mode, and there is no expansion header
with SPI. The 3.5 mm jack is headphone only and the speaker outputs of
the codec are not connected.

Add a device tree for the board that includes the ODROID-U3 one and
describes only these differences, as the ODROID-X2 does with the
ODROID-X, and update the comments in the common dtsi, as the LDO22 and
BUCK8 constraints are now also used by the ODROID-U2.

Also route "HiFi Capture" to "Mixer DAI RX", as on the ODROID-XU3. The
odroid sound card driver adds only the playback routes for boards with
a single CPU DAI, so without it the DPCM capture path to the I2S
back-end is incomplete and recording from the digital microphone fails
with "no backend DAIs enabled for Primary".

Link: https://www.hardkernel.com/shop/odroid-u2/
Link: https://www.hardkernel.com/blog-2/odroid-u2-u-schematics/
Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>
---
 arch/arm/boot/dts/samsung/Makefile            |  1 +
 .../dts/samsung/exynos4412-odroid-common.dtsi |  6 +--
 .../boot/dts/samsung/exynos4412-odroidu2.dts  | 42 +++++++++++++++++++
 3 files changed, 46 insertions(+), 3 deletions(-)
 create mode 100644 arch/arm/boot/dts/samsung/exynos4412-odroidu2.dts

diff --git a/arch/arm/boot/dts/samsung/Makefile b/arch/arm/boot/dts/samsung/Makefile
index e0143ee8c82d..2a173e4b3e1a 100644
--- a/arch/arm/boot/dts/samsung/Makefile
+++ b/arch/arm/boot/dts/samsung/Makefile
@@ -16,6 +16,7 @@ dtb-$(CONFIG_ARCH_EXYNOS4) += \
 	exynos4412-i9305.dtb \
 	exynos4412-itop-elite.dtb \
 	exynos4412-n710x.dtb \
+	exynos4412-odroidu2.dtb \
 	exynos4412-odroidu3.dtb \
 	exynos4412-odroidx.dtb \
 	exynos4412-odroidx2.dtb \
diff --git a/arch/arm/boot/dts/samsung/exynos4412-odroid-common.dtsi b/arch/arm/boot/dts/samsung/exynos4412-odroid-common.dtsi
index 93ddbd4b0a18..b56b92c78c1d 100644
--- a/arch/arm/boot/dts/samsung/exynos4412-odroid-common.dtsi
+++ b/arch/arm/boot/dts/samsung/exynos4412-odroid-common.dtsi
@@ -414,8 +414,8 @@ ldo21_reg: LDO21 {
 
 			ldo22_reg: LDO22 {
 				/*
-				 * Only U3 uses it, so let it define the
-				 * constraints
+				 * Only U2 and U3 use it, so let them define
+				 * the constraints
 				 */
 				regulator-name = "LDO22";
 				regulator-boot-on;
@@ -486,7 +486,7 @@ buck7_reg: BUCK7 {
 			buck8_reg: BUCK8 {
 				/*
 				 * Constraints set by specific board: X,
-				 * X2 and U3.
+				 * X2, U2 and U3.
 				 */
 				regulator-name = "BUCK8_2.8V";
 			};
diff --git a/arch/arm/boot/dts/samsung/exynos4412-odroidu2.dts b/arch/arm/boot/dts/samsung/exynos4412-odroidu2.dts
new file mode 100644
index 000000000000..bc14df9be9f7
--- /dev/null
+++ b/arch/arm/boot/dts/samsung/exynos4412-odroidu2.dts
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Hardkernel's Exynos4412 based ODROID-U2 board device tree source
+ *
+ * Copyright (c) 2026 Josef Schlehofer <pepe.schlehofer@gmail.com>
+ *
+ * Device tree source file for Hardkernel's ODROID-U2 board which is based
+ * on Samsung's Exynos4412 SoC. The board is the predecessor of the
+ * ODROID-U3, so only the differences from it are described here.
+ */
+
+#include "exynos4412-odroidu3.dts"
+
+/ {
+	model = "Hardkernel ODROID-U2 board based on Exynos4412";
+	compatible = "hardkernel,odroid-u2", "samsung,exynos4412", "samsung,exynos4";
+};
+
+/* No VBUS supply switch on the micro-USB port */
+/delete-node/ &vbus_otg_reg;
+
+&hsotg {
+	dr_mode = "peripheral";
+	/delete-property/ vbus-supply;
+};
+
+&sound {
+	model = "Odroid-U2";
+	audio-routing = "Headphone Jack", "HPL",
+			"Headphone Jack", "HPR",
+			"DMICL", "DMIC",
+			"DMICR", "DMIC",
+			"Mixer DAI RX", "HiFi Capture";
+	samsung,audio-widgets =
+		"Headphone", "Headphone Jack",
+		"Microphone", "DMIC";
+};
+
+/* No expansion header with SPI */
+&spi_1 {
+	status = "disabled";
+};
-- 
2.54.0 (Apple Git-157)